Buttler, who came in the 11th over, sent the Sri Lankan bowlers on a leatherhunt as England fetched 72 runs in the final five overs.
Having bagged a fat IPL contract with the Mumbai Indians, Buttler showed why he is so sought after in the shortest format, as he hit eight boundaries and three huge sixes in his 37-ball knock.
With skipper Eoin Morgan (22), Buttler added 74 runs for the fourth wicket in only 6.3 overs.
The momentum shifted in England's favour in the 16th over bowled by Thisara Perera in which 18 runs were scored. Skipper Morgan first whipped Thisara over short fine leg for a boundary and then lofted him over long-off for a six.
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The over set the perfect platform for acceleration in the final four overs. In the very next over, Buttler hit Dusmantha Chameera through covers and a straight hit for a one bounce four. The third one was a cheeky boundary through point region as 14 came off that over.
There were few significant partnerships including 61 for the second wicket between Jason and Joe Root (25).
To describe the pitch, it would be fair to say that the ball was gripping and there was some slow turn on offer with the occasional deliveries keeping low.
Strokemaking wasn't easy which prompted skipper Angelo Mathews to straightaway bring in his premier bowler Rangana Herath into action in the very second over.
Mathews introduced leg-spinner Jeffrey Vandersay to replace himself. But Root and Roy, who had scripted a mammoth run-chase against South Africa showed impressive footwork to smother any turn that was on offer while on occasion they played for the spin.
Both got a few boundaries in the bargain through cuts, firm pushes and the reverse sweeps.
Root was content to the play the second fiddle as Roy took charge post Powerplay overs as he got a couple of sixes charging down to the left-arm spin duo of Herath and Milinda Siriwaradene.
The 50-run stand came off 48 balls as England reached 65 for one at the halfway stage. From there, Buttler took over to make a competitive total look comprehensive.